Attachment means for turbofan low compressor assembly



April 2, 1968 D. L. FITTON 3,375,971

ATTACHMENT MEANS FOR TURBOFAN LOW COMPRESSOR ASSEMBLY Filed Sept. 1,1966 2 Sheets-Sheet l FIGJ Z7 Z5; f jfl :2 d A7 Z6 INVENTOR DA ID LFIT'TON ATTORNEY April 2, 1968 D. L. FITTON 3,375,971

ATTACHMENT MEANS FOR TURBOFAN LOW COMPRESSOR ASSEMBLY Filed Sept. 1,1966 FIClZ 2 Sheets-Sheet 3 l N V E N TOR w L- I'TTON BY Z/V/LW ATTORNEYUnited States Patent 3,375,971 ATTACHMENT MEANS FOR TURBOFAN LOWCOMPRESSOR ASSEMBLY David L. Fitton, East Hartford, Conn., assignor toUnited Aircraft Corporation, East Hartford, Conn., a corporation ofDelaware Filed Sept. 1, 1966, Ser. No. 576,759 7 Claims. (Cl. 230--133)This invention relates to a fan type of gas turbine engine andparticularly to an arrangement for positioning the low pressurecompressor assembly and fan exit guide vanes within the engine.

In the assembly of this portion of the fan engine, it is desirable andadvantageous to dynamically balance the fan and low pressure compressorassembly and then remotely attach this assembly to the turbofan engine.To this extent one feature of the invention is the unitary assembly ofthe fan exit guide vane and low pressure compressor within the engine asa unit.

In this type of engine, it is conventional to provide support for thecompressor stators within the compressor case and then support thecompressor case by an intermediate case. Since the compressor statorsare subject to heavy air loads, it is necessary to transmit this load tothe intermediate case as directly as possible. Another feature of theinvention is an arrangement by which the axial and tangential loads onthe compressor stator vanes are transmitted to the intermediate casingfrom the compressor stators.

Other features and advantages will be apparent from the specificationand claims and from the accompanying drawings which illustrateembodiments of the invention.

FIG. 1 is a sectional view of the position of the compressor and fan ofa fan type engine showing the device of the invention thereof.

FIG. 2 is a sectional view on a larger scale of the top half portion ofthe intermediate casing and the attaching parts to the splitterassembly.

FIG. 3 is a sectional view of a larger scale of the attaching parts ofthe splitter assembly.

FIG. 4 is a sectional view substantially along the line 4-4 in thenon-rotated position.

FIG. 5 is a sectional view substantially along the line 44 in therotated position.

Referring first to FIG. 1, the engine has an outer casing 2, anintermediate casing 4 and an inner casing 6. These cases are held inconcentric relation to one another by radial struts 8. Extending betweena fan casing which is attached to the upstream end of outer casing 2 anda flow splitter 12 attached to the upstream end of intermediate casing 4is a row of fan exit guide vanes 14. A row of compressor stator vanes 16extend between the flow splitter and an inner support ring 18. The outerend of the stator vanes are supported by the flow splitter and the innerend is secured by bolts 17 extending through the inner support ring andstator vane flange 19. In the present embodiment of the invention,single rows of vanes are illustrated; however, any number of rows may beemployed.

Compressor rotor disc 20 and fan disc 21 support and rotate a row ofcompressor blades 22 and a row of fan blades 23. The rows of blades areon opposite sides of the row of compressor stator vanes 16. While onlytwo stages of blades are illustrated the invention is not limited tothis number. Tie rod 24 connects and provides support for the rotordiscs. A spacer sleeve 25 spaces the discs and carries seal flanges 27cooperating with a seal ring 29 on the inner end of stator 16. Thecompressor disc 20,

has an integral mounting flange 31 which connects with a turbine drive,not shown here.

Now referring to FIG. 2, the intermediate casing carries an outwardlyprojecting flange 26. A first ring 28 which surrounds the tips of blades22 carries an outwardly projecting flange 30 and is rigidly secured tothe intermediate casing by rivets 32. At the forward end of ring 28 areoutwardly projecting lugs 34. The intermediate casing also carriesaxially directed circumferential fingers 36. These fingers are distallyspaced from the intermediate casing, thereby forming a plurality ofcircumferentially aligned grooves. Both the outwardly projecting lugs 34and the circumferential fingers 36 are axially aligned.

Referring to FIG. 3, the flow splitter carries spaced circumferentialsplines 38. The spacing between the splines is sufficient to accommodatelugs 34 and permit a slight angular rotation of the splines between thelugs. After this rotation, the splines and lugs are in contact, FIG. 5,and the circumferential loads are thereby transmitted to theintermediate casing. A ring 42, connected to the flow splitter by rivets40, carries inwardly projecting tangs 44. These tangs are axiallyaligned with splines 38 and cooperate within the groove formed by thecircumferential fingers 36 and the intermediate casing. The axialalignment and arrangement of the parts is such that when the splines 38and lugs 34 are in contact, the tan'gs 44 and circumferential fingers 36are in axial alignment and in contact thereby transmitting the axialloads to the intermediate casing. The before and after angular rotationposition of the lugs and splines is illustrated by FIG. 4 and FIG. 5.

The outer end of the fan exit guide vanes 14 carries an outwardlyprojecting flange 46. This flange is riveted or otherwise attached toflange 48 carried by the fan casing 10 and cooperates with flange 50carried by the outer casing. After the fan and compressor assemblyconsisting of'fan casing 10, flow splitter 12, guide vanes 14, statorvanes 16, compressor rotor discs 20 and 21, and rotor blades 22 and 23has been attached to the intermediate casing by mating the splines withthe lugs, and the tangs with the circumferential fingers, the fan andcompressor assembly is rotated causing contact between respectively thesplines and lugs and the tangs and circumferential fingers. Thisrotation aligns the bolt holes in flanges 46, 48 and 50 and the wholeassembly is then locked in place by bolts 52.

It is apparent that the arrangement presents a readily detachablestructure which is positioned within the engine as a unitary assemblyand which may be readily removed by removing bolts 52 and rotating thefan and compressor assembly.

It is to be understood that the invention is not limited to the specificdescription above or to specific figures shown, but may be used in otherways without departure from its spirit as defined by the followingclaims.

I claim:

1. In a turbofan engine, a compressor stator vane support assembly,comprising:

a fan casing,

a splined flow splitter, concentric with said fan casing,

a ring connected to the aft end of said flow splitter,

said ring having a plurality of inwardlly projecting tangs, said tangsbeing axially aligned with said splines,

an inner support ring concentric with and said flow splitter,

a row of guide vanes extending between said fan casing and said flowsplitter, said guide vanes being consaid fan casing nected to said flowsplitter at one end and to said fan casing at the other end, and

at least one row of compressor stator vanes extending between said flowsplitter and said inner support ring, said stator vanes being connectedto said flow 3 splitter at one end and to said inner support ring at theother end.

2. In a turbofan engine, a fan and compressor stator vane assembly,comprising:

an outer casing,

a fan casing,

an intermediate casing concentric with said outer casing, saidintermediate casing having a plurality of circumferential, axiallydirected fingers,

a first ring connected to the forward end of said intermediate casing,said first ring having a plurality of outwardly projecting lugs, saidfingers and lugs being in axial alignment,

a splined flow splitter, said splines being in cooperation with saidlugs,

a second ring connected to the aft end of said flow splitter, said ringhaving a plurality of inwardly projecting tangs, said tangs and saidsplines being axially aligned, and said tangs being in cooperation withsaid fingers,

an inner casing concentric with said outer casing and said intermediatecasing,

at least one row of struts extending between and connecting,respectively, said outer casing, said intermediate casing and said innercasing,

an inner support ring,

a row of guide vanes extending between said fan casing and said flowsplitter, said guide vanes being connected to said flow splitter at oneend and said fan casing at the other end and,

at least one row of compressor stator vanes extending between said flowsplitter and said inner casing ring, said stator vanes being connectedto said flow splitter at one end and to said inner casing at the otherend.

3. In a construction, as in claim 2, in which said splines are spacedpermitting angular rotation of the cooperating lugs therebetween, saidlugs and said splines being in contact after said angular rotation so asto transmit the circumferential loads to said intermediate casing.

4. In a construction, as in claim 2, in which said fingers are distallyspaced from said intermediate casing thereby forming grooves, said tangscooperating in said grooves and being axially aligned with said fingersafter said angular rotation so as to A transmit the axial loads to saidintermediate casing.

5. In a construction, as in claim 3, in which said fingers are distallyspaced from said intermediate casing thereby forming grooves, said tangscooperating in said grooves and being axially aligned with said fingersafter said angular rotation so as to transmit the axial loads to saidintermediate casing.

6. A turbofan engine, as in claim 2:

including means for rigidly securing said compressor stator assembly tosaid outer casing as a unitary assembly.

7. In a turbofan engine, a fan and compressor assembly, comprising:

a fan casing,

a splined flow splitter concentric with said fan casing,

a ring connected to the aft end of said flow splitter, said ring havinga plurality of inwardly projecting tangs, said tangs being axiallyaligned with said splines,

an inner support ring concentric with said fan casing and said flowsplitter,

a row of guide vanes extending between said fan casing and said flowsplitter, said guide vanes being connected to said flow splitter at oneend and to said fan casing at the other end,

at least one row of compressor stator vanes extending between said flowsplitter and said inner support ring, said stator vanes being connectedto said flow splitter at one end and to said inner support ring at theother end,

a turbine drive means,

at least one compressor rotor disc, said disc having means forconnecting to said turbine drive means,

at least one row of compressor rotor blades mounted on said disc, saidblades being axially spaced between said compressor stator vanes andcooperating therebetween.

References Cited UNITED STATES PATENTS 3,283,995 11/1966 Fligg 230-1223,330,475 7/1967 Dennison 230-122 FOREIGN PATENTS 895,075 5/1962 GreatBritain.

HENRY F. RADUAZO, Primary Examiner.

1. IN A TURBOFAN ENGINE, A COMPRESSOR STATOR VANE SUPPORT ASSEMBLY,COMPRISING: A FAN CASING, A SPLINED FLOW SPLITTER, CONCENTRIC WITH SAIDFAN CASING, A RING CONNECTED TO THE AFT END OF SAID FLOW SPLITTER, SAIDRING HAVING A PLURALITY OF INWARDLY PROJECTING TANGS, SAID TANGS BEINGAXIALLY ALIGNED WITH SAID SPLINES, AN INNER SUPPORT RING CONCENTRIC WITHSAID FAN CASING AND SAID FLOW SPLITTER,